Archive for category Activator V

Abstract

Objective:

The main objective of the study was to explore the effect of Activator manipulation in OVX rats.

Methods:

Animals
The protocol, using a limited number of female Sprague-Dawley rats (6 months of age) (Charles Rivers International, Barcelona, Spain) undergoing either shamoperation (Sh) (n=10) or ovariectomy (OVX) (n=15), was approved by the Institutional Animal Care and Use Committee at the IIS-Fundación Jiménez Díaz, according to the European Union guidelines for decreasing animal pain. We complied with the 3R (‘‘replace, reduce, and refine”) experimental design recommendation aimed to reduce the number of experimental animals [21]. Rats were placed in cages under standard conditions (room temperature 20 ± 0.5ºC, relative humidity 55 ± 5% and illumination with a 12 h/12 h light/dark photoperiod), given food and water ad libitum and allowed to move without restriction.

Animal procedures
Both Sh and OVX rats were weighed and divided in two groups, respectively: not manipulated (NM) animals or those manipulated (M) using the setting 1 of the Activator V Adjusting Instrument® (Activator Methods International, Phoenix, AZ) with preload of 3.705 pounds/inch spring rate, applied onto the tibial tubercle at a 90º angle from medial to lateral side [22]. In rats of the M group (Sh =5, OVX=10), right hind limbs were adjusted with true chiropractic manipulation (TM), whereas corresponding left hind limbs were subjected to false chiropractic manipulation (FM) by firing the Activator V in the air and gently touching the tibial tubercle. These procedures were repeated 3 times/week for 6 weeks, starting once bone loss was confirmed in OVX rats (10 weeks after OVX). At the end of treatments, bone mass was determined in anesthetized (ketamine/xilacine) rats. Thereafter, animals were sacrificed by isoflurane inhalation, followed by removal of the long bones, spine and muscles (quadriceps femoris, soleus, tibialis anterior and tibialis posterior) for analysis as described below

Results:

Chiropractic manipulation improves OVX-related bone loss in rats
Although total body weight was higher in OVX rats than in Sh animals (456 ± 12 g vs 351 ± 8 g, respectively; p<0.01), bone loss occurred in the former rats as confirmed by DXA. In the long bones and vertebrae of NM-OVX rats (similar to that in FM-OVX rats when appropriate), bone mass parameters were lower than those in Sh animals (Table 1a). ActivatorV® adjustment in the tibial tubercle of the right hind limbs produced higher BMD and BMC in both the distal femur and the proximal tibia of OVX rats (TM group), even though not reaching the corresponding values in Sh rats (Table 1b). In contrast, BMD and BMC values in the proximal femur or L3-L4 vertebrae (axial bone subjected to physiological mechanical loading) were similar in both manipulated and not manipulated groups of OVX rats (Tables 2 and 3). BMD and BMC values were similar in both the long bones and vertebrae among all experimental groups of Sh rats

Chiropractic manipulation compensates in part trabecular bone alterations induced by OVX in rats
Next, we aimed to confirm whether the aforementioned improvement of bone mass was related to parallel changes in bone structure elicited by the chiropractic manipulation in OVX rats. Using CT, we evaluated several trabecular and cortical bone parameters in the long bones of the different groups of rats studied. Consistent with the observed bone mass loss in OVX rats, BV/TV and Tb.N were found to be lower, and Tb.S higher, in trabecular bone of the distal femur and the proximal tibia in both NM-OVX and FM-OVX groups of rats, compared to those in NM-Sh rats (Tables 4 and 5). It is worth noting that the TM-OVX group showed a significant improvement of these bone structure parameters (BV/TV, Tb.N and Tb.S) at both skeletal locations (Table 5). In contrast, we failed to detect any significant change in the cortical bone parameters tested (Ct. Th and M.Ar) in OVX rats, subjected or not to chiropractic manipulation (Table 5).

Chiropractic manipulation counteracts the low muscle MGF protein expression in OVX rats
We also evaluated whether chiropractic stimulus produced by the Activator V® would affect MGF production in rat skeletal muscles, related to the observed bone alterations in OVX rats. A lower MGF protein expression was observed in the quadriceps femoris, and in the tibialis anterior and posterior, but not in the soleus in NM-OVX rats in comparison to the NM-Sh group (Fig.1). This difference was counteracted by chiropractic manipulation (TM-OVX group) in both the quadriceps femoris and tibialis anterior (Fig.1). In view of these results, we decided to confirm whether TM on the right hind limbs of OVX rats could affect the FM on the contralateral hind limbs of these rats. Thus, we compared the expression of MGF in quadriceps femoris and tibialis anterior between both hind limbs in both Sh and OVX rats. We failed to observe any significant alteration in this protein expression between the left and the corresponding right muscles in both NM-Sh and NM-OVX groups, although these values of the latter group were lower than those of the former group (Fig. 2). Moreover, these values were similar in both NM-OVX and FM-OVX rats. On the other hand, higher levels of MGF protein occurred in these muscles of TM-OVX rats, compared to FM-OVX rats, confirming the local action of Activator V® (Fig.2)

Chiropractic manipulation interferes with the elevated MGF expression in the long bones of OVX rats
Considering the observed variations in MGF protein expression in the rat skeletal muscle, we proceeded to assess the possible MGF alterations which might have occurred in the rat long bones associated with Activator V® manipulation in OVX rats. We focused on osteocytes, which express MGF and are the most abundant cells in the cortical bone matrix. In both femur and tibia, MGF immunostaining in these cells was increased in OVX rats, compared to that in the NM-Sh group, but this increase was abrogated by chiropractic manipulation in these rats (Fig. 3).

Conclusion:

In conclusion, even considering the limitations of the present pre-clinical study as stated above in the Discussion, the present findings support the notion that chiropractic manipulation can improve osteoporotic bone at least in part by targeting skeletal muscle. This experimental study provides novel scientific data that open new avenues to supporting the application of chiropractic manipulation in bone loss-related situations.


Author information: A. López-Herradón, R. Fujikawa, M. Gómez-Marín, J. P. Stedile-Lovatel, F. Mulero, J. A. Ardura, P. Ruiz, I. Muñoz, P. Esbrit, I. Mahíllo-Fernández, A. Ortega-de Mues. Madrid College of Chiropractic; Madrid, Spain.

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Abstract

Objective:

The purpose of this preliminary study is to determine muscle spindle response characteristics related to the use of 2 solenoid powered clinical mechanically assisted manipulation (MAM) devices.

Methods:

L6 muscle spindle afferents with receptive fields in paraspinal muscles were isolated in 6 cats. Neural recordings were made during L7 MAMthrusts using the Activator V (Activator Methods Int. Ltd., Phoenix, AZ) and/or Pulstar (Sense Technology Inc., Pittsburgh, PA) devices at their 3 lowest force settings. Mechanically assisted manipulation response measures included (a) the time required post-thrust until the first action potential, (b) differences in mean frequency (MF) and mean instantaneous frequency (MIF) 2 seconds before and after MAM, and (c) the time required for muscle spindle discharge (MF and MIF) to return to 95% of baseline after MAM.

Results:

Depending on device setting, between 44% to 80% (Pulstar) and 11% to 63% (Activator V) of spindle afferents required N6 seconds to return to within 95% of baseline MF values; whereas 66% to 89% (Pulstar) and 75% to 100% (Activator V) of spindle responses returned to within 95% of baseline MIF in b6 seconds after MAM. Nonparametric comparisons between the 22N and 44N settings of the Pulstar yielded significant differences for the time required to return to baseline MF and MIF.

Conclusion:

Short duration (b10 ms) MAM thrusts decrease muscle spindle discharge with a majority of afferents requiring prolonged periods (N6 seconds) to return to baseline MF activity. Physiological consequences and clinical relevance of described MAM mechanoreceptor responses will require additional investigation.


Author information: William R. Reed, DC, PhD, Joel G. Pickar, DC, PhD, Randall S. Sozio, BS, LATG, Michael A.K. Liebschner, PhD,  Joshua W. Little, DC, PhD, and Maruti R. Gudavalli, PhD. Palmer Center for Chiropractic Research, Palmer College of Chiropractic, Davenport, IA.

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Abstract STUDY DESIGN: Comparative study using robotic replication of spinal manipulative therapy (SMT) vertebral kinematics together with serial dissection. OBJECTIVE: The aim of this study was to quantify loads created in cadaveric spinal tissues arising from three different forms of SMT application. SUMMARY OF BACKGROUND DATA: There exist many distinct methods by which to apply […]

Abstract

STUDY DESIGN:

Comparative study using robotic replication of spinal manipulative therapy (SMT) vertebral kinematics together with serial dissection.

OBJECTIVE:

The aim of this study was to quantify loads created in cadaveric spinal tissues arising from three different forms of SMT application.

SUMMARY OF BACKGROUND DATA:

There exist many distinct methods by which to apply SMT. It is not known presently whether different forms of SMT application have different effects on spinal tissues. Should the method of SMT application modulate spinal tissue loading, quantifying this relation may help explain the varied outcomes of SMT in terms of effect and safety.

METHODS:

SMT was applied to the third lumbar vertebra in 12 porcine cadavers using three SMT techniques: a clinical device that applies forces through a hand-held instrument (INST), a manual technique of applying SMT clinically (MAN) and a research device that applies parameters of manual SMT through a servo-controlled linear actuator motor (SERVO). The resulting kinematics from each SMT application were tracked optically via indwelling bone pins. The L3/L4 segment was then removed, mounted in a parallel robot and the resulting kinematics from SMT replayed for each SMT application technique. Serial dissection of spinal structures was conducted to quantify loading characteristics of discrete spinal tissues.

RESULTS:

In terms of load magnitude, SMT application with MAN and SERVO created greater forces than INST in all conditions (P < 0.05). Additionally, MAN and SERVO created comparable posterior forces in the intact specimen, but MAN created greater posterior forces on IVD structures compared to SERVO (P < 0.05).

CONCLUSION:

Specific methods of SMT application create unique vertebral loading characteristics, which may help explain the varied outcomes of SMT in terms of effect and safety.


Spine (Phila Pa 1976). 2017 May 1;42(9):635-643. PMID: 28146021 

Author information: Funabashi M, Nougarou F, Descarreaux M, Prasad N, Kawchuk GN. University of Alberta, Edmonton, AB, Canada.


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Abstract

OBJECTIVE:

The objectives of this study were to determine the ability of several commercial shockwave devices to achieve a desired thrust profile in a benchtop setting, determine the thrust profile in a clinical analog, and determine the influence of operator experience level on device performance.

INTERVENTION AND OUTCOME:

We conducted two different types of testing: (1) bench testing to evaluate the devices themselves, and (2) clinical equivalent testing to determine the influence of the operator.

CONCLUSIONS:

The results indicated a significant dependence of thrust output on the compliance of the test media. The Activator V-E device matched the ideal half-sine thrust profile to 94%, followed by the Impulse device (84%), the Activator IV/FS (74%), and the Activator II (48%). While most devices deviated from the ideal profile on the return path, the Impulse device exhibited a secondary peak. Moreover, the Activator V-E device provided evidence that the device performs consistently despite operator experience level.This has been a major concern in manual spinal manipulation. Based on our results, a hyper-flexible spine would receive a lower peak thrust force than a hypo-flexible spine at the same power setting. Furthermore, a hand-held operation further reduced the peak thrust force as it increased the system compliance. However, that influence was dissimilar for the different devices. Although controlled clinical trials are needed to determine the correlation between thrust profile and clinical outcome, already ongoing clinical studies indicate an improved patient satisfaction due to reduced treatment pain when devices are used with a thrust characteristic closer to an ideal sine wave.


Annals of Biomedical Engineering, Vol. 42, No. 12, December 2014 ( 2014) pp. 2524–2536 DOI: 10.1007/s10439-014-1115-4

Author information: Liebschner, Michael A. K.; Chun, Kwonsoo; Kim, Namhoon; and Ehni, Bruce

Department of Neurosurgery, Baylor College of Medicine, Houston, TX, USA; Research Service Line, Michael E. DeBakey VA Medical Center, Houston, TX, USA;  Exponent Failure Analysis, Houston, TX, USA;  Department of Pediatrics Cardiology, Baylor College of Medicine, Houston, TX, USA; and Neurosurgery Service Line, Michael E. DeBakey VA Medical Center, Houston, TX, USA

In Vitro Biomechanical Evaluation of Single Impulse and Repetitive

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